GeoScience Enginee ing Vol. 70 (2024), No. 2
geoscience.cz pp. 40–50, ISSN 1802-5420
DOI 10.35180/gse-2024-0111
A LABORATORY STUDY ON USE OF SCREW-TYPE FRICTION
BOLTS AS NEW SOFT ROCK STABILIZERS
E en KOMURLU 1
1 Gi esun Uni e si y, Facul y o Enginee ing, Depa men o Ci il Enginee ing, Gi esun, Tu key
E-mail: ekomu lu@gi esun.edu. ,
ABSTRACT
In his s udy, load bea ing capaci ies o sc ew bol s as a new ic ion bol ype was in es iga ed ca ying ou a
se ies o labo a o y s udies. New sc ew- ype ic ion bol s wi h sha p h eads we e inse ed in o holes d illed in
a ious so ocks by applying o a ion. Sc ew bol s and spli se s inse ed in di e en so ock ypes we e
in es iga ed o compa a i ely e alua e hei load bea ing capaci y alues. Acco ding o he esul s ob ained om
his s udy, new sc ew bol s we e ound o supply be e load bea ing capaci y alues han hose o he spli se s.
Al hough he spli se s a e qui e popula ic ion bol s used in ock enginee ing, hey ha e signi ican disad an ages
esul ing om hei poo ancho age pe o mances in so ocks. By making g oo es on d ill hole con ac su aces,
inc eased coe icien o ic ion and load bea ing capaci y alues can be supplied by new sc ew bol s which we e
ound o be ad an ageous o using in so ocks.
Keywo ds: F ic ion bol s; Openings in so ocks; Rein o cing so ocks; Rock bol s; Sc ew bol s.
1 INTRODUCTION
Rock bol s which a e widely used o ein o ce mining and ci il enginee ing exca a ions can be classi ied in
acco dance wi h di e en pa ame e s such as g ou usage (g ou ed o ic ion bol s), g ou ype (cemen , esin,
e c.), shank body ma e ial (s eel, polyme ic composi es, e c.), p e- ensioning p ope ies (ac i e, passi e), ene gy
abso p ion capaci ies (ene gy-abso bing bol s and o he s) and e c. [1-6]. G ou ed ock bol s ha e g ou bonds
be ween he ock and bol su aces. On he o he hand, ic ion bol s ha e he abili y o bea ing load wi hou using
g ou ma e ials. The ic ion ype ock bol s supply suppo p essu e by he ic ion o ces a he con ac o he bol
shanks and ock su aces o he d ill holes. The mos popula and economical ic ion bol s, spli se s a e qui e
simple and only consis o a ube body and a ma ching pla e pa .
Load bea ing capaci ies o ock bol s depend on a ious pa ame e s. No ma e how s ong he bol is, he load
bea ing capaci y is limi ed by he ock s eng h in poo ock masses. Gene ally, ock bol s can no supply a good
bea ing capaci y o he s abiliza ion o exca a ions in so ocks because o he low ancho age pe o mances in
he low s eng h ock masses. E en i a s ong s eel shank body is used in so ock masses, a good bea ing capaci y
can no be gene ally supplied by bol ing as a esul o he absence o an enough ancho age capaci y [7-9].
Addi ionally, he wa e y d illing p ocess can make signi ican dec eases in s eng h alues o he so ock masses
like hose wi h he poo slake du abili y p ope y. Because he ock s eng h is a de e mina i e pa ame e o he
ic ion coe icien o he d ill hole and bol con ac , ic ion bol s like spli se s some imes exhibi undesi ed load
bea ing pe o mances in so ocks [10, 11]. Simila ly, g ou ed ock bol pe o mances also depend on he ock
s eng h pa ame e [12, 13]. The main mo i a ion o his s udy is o design and in es iga e a new ic ion bol o
supply imp o ed bea ing capaci y alues in so ocks.
The newly designed ock bol s ha e sc ew-like shanks wi h sha p h eads o imp o e adhe ence in d ill holes. The
sc ew-like new bol s a e inse ed in o he d ill holes by o a ing. The sc ew ancho s a e also used in soil masses
by using no d ill hole [14-16]. Conside ing hei usabili y in ock masses, i is es ima ed ha i is no possible o
ins all sc ew ype new ock bol s wi hou d ill holes excep o ex emely so ocks. The e o e, he holes mus be
d illed o inse he sc ew ype new ock bol s in o he ock masses. The e a e wo di e en diame e s o sc ew
41
GeoScience Enginee ing Vol. 70 (2024), No. X
geoscience.cz pp. 40–50, ISSN 1802-5420
DOI 10.35180/gse-2024-0111
ype bol s, which a e ou e (do) and inne diame e s (di). To make a good coupling, he ou e diame e (do) o he
new ock bol s should be selec ed highe han he d ill hole diame e . Howe e , he inne diame e (di) should be
selec ed o be lowe han he d ill hole diame e o he ease o he inse ion. Because o hei sc a chabili y, so
ock su aces can be ad an ageous in e ms o inc easing he con ac oughness and hus he ancho ing pe o mance
o he sc ew h eads.
Some physical p ope ies o he new bol s a e gi en in Figu e 1. I was aimed o use sc ew bol s o u n he so ness
o he ock su aces in o an ad an age. Fo he ans e o ock c umbs occu ed du ing ins alla ion, he pi ch and
he h ead dep h (do-di) a e impo an physical pa ame e s o be selec ed enough high in e ms o inse ion
p ac icali y o he new bol designs. On he o he hand, i should be conside ed o an op imal design ha big
pi ches cause a dec ease in he h ead numbe and he adhe ence pe o mance. As ano he impo an equi emen ,
h ead c es s o he new ock bol s mus be sha p o easily make sc a ches on he so ock su ace and supply an
imp o ed adhe ence in d ill holes. Since he sc ew bol s a e inse ed by o a ion, hey can ha e co ne ed ends like
iangle, squa e o hexagonal shaped ones o be p ope ly g ipped. The e a e a ious design pa ame e s o he
sc ew bol s o selec a p ope ein o cemen o a ele an so ock mass. I should be eminded he ein ha he
sc ew bol s a e in es iga ed only o so ocks wi hin his s udy.
Use o no g ou ma e ial can be assessed o be an impo an ad an age especially because o he abili y o s a
load bea ing immedia ely a e he inse ion wi hou a need o wai g ou cu ing eac ions [17-19]. Sc ew bol s can
ha e pipe ype hollow bodies o solid c oss-sec ions. Since o he ic ion bol s ha e no solid bodies, sc ew bol s
a e es ima ed o supply signi ican ly highe body s eng hs han hose o he popula hollow body bol s like spli
se s and swellex ypes. Wi hin his s udy, i was in es iga ed o assess whe he he sc ew ype new ock bol s a e
ad an ageous in e ms o p o iding highe load bea ing capaci y alues in compa ison wi h o he ic ion bol
ypes. The new sc ew bol design de ails a e gi en in he ollowing sec ion.
Figu e 1. Some physical p ope ies o sc ew bol s
2 MATERIALS AND METHODS
Load bea ing pe o mances o he new sc ew bol s in a ious so ock ma e ials we e in es iga ed wi hin he
labo a o y s udy. In he labo a o y es s, u , daci ic u , sands one and clayey limes one ype ou di e en ocks
we e used o de e mine he new bol pe o mances. Tu , daci ic u , sands one and clayey limes one samples a e
so ocks which ha e he uniaxial comp essi e s eng h (UCS) alues o 13 MPa, 18 MPa, 16 MPa and 21 MPa,
espec i ely. The UCS es s we e ca ied ou by using ock co e specimens wi h he NX size diame e . The UCS
es s we e ca ied ou o ge an idea abou he ock ma e ials used in he bol ancho age es s. Acco ding o he
ISRM (2007), all he UCS es specimens we e cu o ha e he heigh o diame e a io o 2.5 and we e loaded
unde a comp essi e s eng h es p ess (Figu e 2) [20].
The ock ma e ials we e also examined by using he geological hamme . All he used ock ma e ials had
inden a ions made by a i m blow wi h he poin o he geological hamme . Addi ionally, su aces o all he ock
ma e ials es ed in his s udy can be sc a ched by he pocke kni e. Acco ding o bo h UCS es and he geological
hamme in es iga ions, ock ma e ials used in his s udy can be classi ied as weak ock ma e ials [21-23].
Acco ding o he examina ion wi h he geologis hamme , he so es one wi hin he es ed ocks was p ac ically
assessed o be he u samples, and he ela i ely ha de one was de e mined o be he clayey limes one. To
42
GeoScience Enginee ing Vol. 70 (2024), No. X
geoscience.cz pp. 40–50, ISSN 1802-5420
DOI 10.35180/gse-2024-0111
illus a e i s so ness p ope y, Figu e 3 shows ha i was ound able o inse a s eel sc ew wi h he ou e diame e
o 8 mm in o a u block by hand powe wi hou making a d ill hole.
Figu e 2. a) Rock specimen co ing, b) co e cu ing, c) uniaxial comp essi e s eng h es ing
Figu e 3. A small diame e sc ew inse ion by hand
The clayey limes one, sands one and u blocks we e egula ly cu blocks om he No h-Eas e n and Eas e n
egions o Tu key. On he o he hand, daci ic u samples had no sawed su aces and we e b ough om an
unde g ound coppe mine in he Black Sea Region o Tu key. Among he daci ic u blocks in he mine, ela i ely
egula shape ones we e selec ed and b ough o he labo a o y o be d illed o he bol inse ion.
Wi hin his expe imen al s udy, ock blocks we e d illed by using a s and d ille machine (Figu e 4). Fo he
p epa a ion o sc ew bol inse ed holes, a d ill bi wi h a diame e o 24 mm was used. In he labo a o y es s,
leng h o d ill holes was 25 cm. The ock bol s used in he labo a o y es s ha e a leng h o 60 cm. The 25 cm pa s
we e inse ed in o he d ill holes by he o a ion o sc ew bol s. The con ac leng h in he hole was 25 cm o all
ock blocks. The inse ion o a ion was supplied by an elec ic machine. To e ec i ely g ip he bol , head pa s o
he sc ew bol specimens we e manu ac u ed o ha e a squa e-shaped c oss sec ion (Figu es 5 and 6). To compa e
hei load bea ing capaci y alues wi h hose ob ained om he sc ew bol specimens, con en ional s eel spli se
specimens we e also used in he expe imen al s udy. Spli se ubes wi h he ou side diame e o 39 mm we e cu
o make an angula on end wi h 45° cu angle o hei inse ion in o he holes d illed by using a 36 mm diame e
bi . Sli s we e on he longe sides o he ubes wi h he angula on end. Using an elec omechanical loading
sys em, spli se s we e pushed in o d ill holes wi h he leng h o 25 cm as seen in Figu e 7.
43
GeoScience Enginee ing Vol. 70 (2024), No. X
geoscience.cz pp. 40–50, ISSN 1802-5420
DOI 10.35180/gse-2024-0111
To de e mine he bea ing capaci ies o he bol s, he pull-ou es which is a amous ancho age es was ca ied ou .
The aim o he pull-ou es is o de e mine he bea ing capaci ies o ock bol s unde he axial loading condi ion
[24-26]. In he pull-ou es , sc ew bol s we e held om he double nu s moun ed a he specially ea ed back ends
o he shanks and pulled by he hyd aulic jack o he es equipmen (Figu e 8). In addi ion o he nu holding
mechanism, he pull-ou es equipmen jaws s ongly g ipped he shanks. The ou e (do) and inne diame e s (di)
o he lab scale sc ew bol s we e 28 mm and 20 mm, espec i ely. The pi ch size o he lab specimens was 4 mm.
In he pull-ou es o spli se samples, immed ings we e assembled o hold he cu ubes. As seen in Figu e 9,
s eel ods we e d i en in d illed holes o he ubes o ix he ings. The ings a he spli se ends we e con ac ed on
he d illed pla e du ing he loading (Figu e 9). D ill hole diame e in ock blocks o spli se ubes' diame e a io
was abou 0.92, which alls wi hin he ypical ange o spli se applica ions [27-29].
Figu e 4. Rock block d illing
3 RESULTS AND DISCUSSIONS
The pull-ou es esul s ob ained om he labo a o y s udy a e gi en in Table 1. Acco ding o esul s, sc ew bol s
we e ound o ha e no ably highe load bea ing capaci ies in compa ison wi h he spli se samples. Sc ew bol s
we e e alua ed o supply app oxima ely 2.5 imes highe bea ing capaci y han hose o he spli se s o he same
con ac leng h in d ill holes. I was de e mined ha sc ew bol s a e much mo e ad an ageous o supply a p ope
load bea ing capaci y pe o mance compa ed o he spli se s.
44
GeoScience Enginee ing Vol. 70 (2024), No. X
geoscience.cz pp. 40–50, ISSN 1802-5420
DOI 10.35180/gse-2024-0111
Figu e 5. a) and b) h ead designs o labo a o y specimens, c) a shown o he squa e-shaped end o he sc ew
bol s, d) a pho o o sc ew bol inse ion in he labo a o y s udy
Figu e 6. Squa e-shaped ends and h eaded pa s o be i ed wi h nu s

45
GeoScience Enginee ing Vol. 70 (2024), No. X
geoscience.cz pp. 40–50, ISSN 1802-5420
DOI 10.35180/gse-2024-0111
Table 1. Pull-ou es esul s ob ained om he labo a o y s udy (Fmax: Maximum load, SN: Numbe o
specimens, SD: S anda d de ia ion)
Rock ype
Sc ew bol samples
Spli se samples
Mean Fmax
(kN)
SN
SD
(kN)
Mean Fmax
(kN)
SN
SD
(kN)
Sands one
29
5
3
11
5
2
Tu
35
4
2
13
4
1
Daci ic u
32
5
4
14
5
3
Clayey limes one
40
5
4
16
5
2
Figu e 7. Inse ion o spli se s in he labo a o y s udy
Figu e 8. Some pho os om pull-ou es s o sc ew bol specimens used in he labo a o y s udy
46
GeoScience Enginee ing Vol. 70 (2024), No. X
geoscience.cz pp. 40–50, ISSN 1802-5420
DOI 10.35180/gse-2024-0111
Figu e 9. Some pho os om pull-ou es s o spli se s (a, b), spli se ubes' holding ing mechanism (c)
This s udy does no include a ield-sized bol design in es iga ion. I is a p elimina y one ca ied ou by using an
ea ly labo a o y-scale sc ew bol design. Fo an imp o emen o i s suppo pe o mance, new h ead and d ill
designs can be in es iga ed wi hin u he s udies. The sc ew bol s we e in es iga ed o so ocks in his s udy.
Wi hin he u u e s udies, special sc ew designs can be also in es iga ed o a po en ial use o he new bol s o
mid s eng h ocks. In all he load bea ing capaci y es s, bol s slid in he ock blocks as he maximum load le el
is achie ed. I can be aimed o design he sc ew h eads o he pu pose o inc ease in he bea ing capaci y o a
le el which makes he ailu e o he body s eel.
Use o a long bol can be an upcoming s udy opic o make a ious h ead designs in sc ew bol applica ions. The
designs o sc ew h eads should be examined in de ail o he ins alla ion o long-dimensional ock sc ews. I is
es ima ed ha he sc ew ype ic ion bol leng hs can be limi ed because o possible high ic ions du ing he
ins alla ion. In his ega d, di e en pi ches, h ead angles, h ead dep hs and some o he de ails like c es sha pness
and ab asion p ope ies can be in es iga ed in u he analyses on he inse ion p ac icali y. One o he signi ican
a ge s in he upcoming designs is hough o be dec easing inse ion ic ions while imp o ing he load bea ing
capaci y alues o he new sc ew bol s.
In case o low adhe ence pe o mances in so ocks, spli se s each hei bea ing capaci y alues which a e a
om he load le els o make he body ailu e [30-32]. E en i a good adhesion is supplied, he ailu e o he s eel
spli se ube body occu s a ypical load le els o 60 kN - 70 kN [33-36]. Because o he qui e limi ed body bea ing
capaci y alues o he ube ailu e, spli se s can no supply he load bea ing capaci ies and suppo p essu es
ob ained om he sc ew bol s wi h he solid c oss-sec ion. As a esul o hei ela i ely low suppo p essu es, he
spli se s a e disad an ageous o wo k well in he poo so ock masses [37-39]. In his s udy, he bea ing capaci y
alues o sc ew bol s in a ious so ocks we e ema kably highe han hose o he spli se s.
Due o he s ess elaxa ion, spli se s can ha e dec eases in he no mal s ess alues ac ing on he ic ion su ace.
I is a well-known ac ha ic ion capaci ies o he spli se s wo sen depending on ime [40-43]. The s ess
elaxa ion can be b ie ly de ined as he dec ease in he s ess alues o a ma e ial kep unde a cons an s ain. The
s ess elaxa ion is a cause o bea ing capaci y losses o he spli se ubes which a e comp essed and kep a a
cons an diame ic s ain in d ill holes. Spli se s ha e sho se ice li e imes which a e usually limi ed o a ew
mon hs. On he o he hand, he sc ew bol is a new candida e o make be e ed se ice li e imes in compa ison
wi h hose o o he ic ion bol s. I is hough ha sc ew bol s may ha e ela i ely longe se ice imes due o hei
ela i ely hick body s uc u e. In u u e s udies, e ec i e se ice li e imes o he sc ew bol s can be examined as
ano he impo an opic o unde s and he long e m suppo p ope ies o he new ock bol . The use o ha d and
co osion esis an su ace coa ings o sc ew bol s can also be ano he opic o u he in es iga ions. Va ious
ypes o ock bol s ha e been imp o ed a e hey we e i s ly p oposed, in consequence o di e en s udies.
Simila ly, sc ew bol s a e belie ed o be made mo e e ec i e wi h new s udies on i s use.
47
GeoScience Enginee ing Vol. 70 (2024), No. X
geoscience.cz pp. 40–50, ISSN 1802-5420
DOI 10.35180/gse-2024-0111
D ill bi diame e is an impo an opic o ock bol ing pe o mances. Weak ock masses can be damaged du ing
he we d illing p ocess. Especially, he p e e ence o la ge hole diame e s inc eases his damage and can cause
so ock masses o be dis u bed [44-46]. I should be eminded he ein ha his s udy was pa icula ly ca ied ou
o so ock masses which can ha e no able s eng h losses due o he d illing p ocesses. As seen in Figu e 10
which is a pho o aken om he mine whe e he daci ic u blocks we e b ough om, he ock mass a ound d ill
holes becomes agmen al by hand a e he wa e y d illing p ocess because o poo slake du abili y and so
su ace p ope ies o he daci ic u ma e ial. Use o he sc ew bol s is also ad an ageous because o using
ela i ely low d ill diame e s. Fo ins ance, i was de e mined ha a no ably highe load bea ing capaci y can be
supplied by he sc ew bol s inse ed in o he holes wi h 24 mm d ill diame e in compa ison wi h he 36 mm d ill
diame e use in he spli se applica ions. Use o ela i ely small diame e d ill holes makes an ad an age o
dec ease s eng h losses o so ock masses.
Figu e 10. A shown o he daci ic u o ma ion: a d ill hole (a) and i s agmen a ion by hand (b)
To deal abou cos s, i can be no ed ha he p ice o shanks o he sc ew bol s wi h he ou side diame e o 28 mm
is 7 USD pe one me e leng h. Adding he p ice o he pla e pa , he o al cos o a 1 me e leng h bol is abou
10.5 USD. The cos is app oxima ely 17.5 USD pe a bol wi h he leng h o 2 m. I should be no ed he ein ha
he p ices gi en abo e a e calcula ed in conside a ion o he cos s paid in 2023 wi hin his s udy. I is o eseen ha
he cos s can be signi ican ly educed o he sys ema ic p oduc ion o a la ge numbe o sc ew bol s in u u e. The
ypical p ice in e al o a comme cial spli se wi h he leng h o 2 m is 8 USD-10 USD pe a bol . Al hough sc ew
bol s may seem expensi e a he i s glance, hey can be conside ed a o dable due o he ad an age o hei high
bea ing capaci y. Sc ew bol s wi h he solid c oss-sec ion we e in es iga ed wi hin his s udy. To dec ease he
ma e ial consump ion and he o e all bol ing cos s, hollow body sc ew bol s can be also in es iga ed wi hin u he
s udies. Sc ew ype new ic ion bol s a e open o e y di e en and no el in es iga ions o be e unde s and
hei ancho age p ope ies and imp o e hei suppo pe o mances.
4 CONCLUSION
Sc ew bol s we e in es iga ed as a new ic ion ype ock bol specimens wi hin his labo a o y scale s udy. Sha p
h eads o sc ew bol s p o ide ough ic ion su aces and good adhe ence p ope ies by sc a ching he d ill hole
walls and c ea ing g oo es on he so ock su ace. Acco ding o he indings, i was ound ha sc ew bol s can
be used o ha e an imp o ed load bea ing capaci y and suppo pe o mance in so ocks compa ed o ypical
ic ion bol s like spli se s. Because his s udy is an ea ly one, u he in es iga ions and si e scale es s will be
highly bene icial o be e unde s and he suppo p ope ies o he no el sc ew bol s o making new and highly
48
GeoScience Enginee ing Vol. 70 (2024), No. X
geoscience.cz pp. 40–50, ISSN 1802-5420
DOI 10.35180/gse-2024-0111
e ec i e designs. The new sc ew bol s we e ound o be ad an ageous o ein o ce so ocks and ha e a good
po en ial o become a popula ic ion bol ype in ock enginee ing.
ACKNOWLEDGEMENT
This s udy has been suppo ed by FEN-BAP-A-250221-16 coded scien i ic esea ch p ojec o Gi esun Uni e si y.
The au ho exp esses his since e hanks o he suppo by he Gi esun Uni e si y Scien i ic Resea ch P ojec s
Coo dina ion Uni .
REFERENCES
[1] LI, C.C.; STJERN, G. and MYRVANG, A. A e iew on he pe o mance o con en ional and ene gy-
abso bing ockbol s. Jou nal o Rock Mechanics and Geo echnical Enginee ing. 2014, ol. 6, no. 4, pp.
315–327. A ailable om: h ps://doi.o g/10.1016/j.j mge.2013.12.008.
[2] SRIVASTAVA, L.P. Analysis o a Rock Bol -Rein o ced Tunnel wi h Equi alen Mechanical P ope ies.
Indian Geo echnical Jou nal. 2022, ol. 52, no. 4, pp. 815–834. A ailable om:
h ps://doi.o g/10.1007/s40098-022-00631-1.
[3] HOLÝ, O. E alua ion o Many Load Tes s o Passi e Rock Bol s in he Czech Republic. GeoScience
Enginee ing. 2017, ol. 63, no. 1, pp. 1–7.
[4] WANG, H.; LI, S.; WANG, Q.; WANG, D.; LI, W. e al. In es iga ing he suppo ing e ec o ock bol s
in a ying ancho ing me hods in a unnel. Geomechanics and Enginee ing. 2019, ol. 19, no. 6, pp. 485–
498. A ailable om: h p://dx.doi.o g/10.12989/gae.2019.19.6.485.
[5] RANJBARNIA, M.; FAHIMIFAR, A. and ORESTE, P. P ac ical me hod o he design o p e ensioned
ully g ou ed ockbol s in unnels. In e na ional Jou nal o Geomechanics. 2016, 16, no. 1, a icle
04015012. h ps://doi.o g/10.1061/(ASCE)GM.1943-5622.0000464.
[6] KOMURLU, E.; CELIK, A.G. and GUNES, I. Use o a new inse ion appa a us o imp o ing
pe o mances o he spli se ype ic ion ock bol s. Mining Me allu gy & Explo a ion. 2022, ol. 39, pp.
413–420. A ailable om: h ps://doi.o g/10.1007/s42461-021-00533-5.
[7] KOMURLU, E. and DEMIR, S. Use o Rock Mass Ra ing (RMR) alues o Suppo Designs o Tunnels
exca a ed in So Rocks wi hou Squeezing P oblem. Geoscience Enginee ing. 2019, ol. 65, no. 2, pp.1–
17. A ailable om: h p://doi.o g/10.35180/gse-2019-0007.
[8] STIMPSON, B. Spli Se ic ion s abilize s: an expe imen al s udy o s eng h dis ibu ion and he e ec o
co osion. Canadian Geo echnical Jou nal. 2011, ol. 35, no. 4, pp. 678–683. A ailable om:
h ps://doi.o g/10.1139/ 98-025.
[9] MA, H.; CHEN, L.; TAN, X.; QIAN, J. and LU, Z. Theo e ical dynamic displacemen analysis o ock
bol wi h su ounding ock-soil body. In e na ional Jou nal o Rock Mechanics and Mining Sciences. 2021,
ol. 141, a icle 104698. A ailable om: h ps://doi.o g/10.1016/j.ij mms.2021.104698.
[10] XU, S., YANG, Z.; CAI, M. and HOU, P. An expe imen al s udy on he ancho ing cha ac e is ics o an
inno a i e sel -swelling Spli -se . Tunnelling and Unde g ound Space Technology. 2021, ol. 112, a icle
103919. A ailable om: h ps://doi.o g/10.1016/j. us .2021.103919.
[11] SHAPOSHNIK, Y.N.; KONURIN, A.I.; NEVEROV, A.A.; NEVEROV, S.A.; USOLTSEVA, O.M. e al.
Valida ion o F ic ion-Ancho ed Rock Bol Suppo s o Unde g ound Exca a ions in Back ill. Jou nal o
Mining Science. 2021, ol. 57, pp. 775–786. A ailable om: h ps://doi.o g/10.1134/S1062739121050070.
[12] PINAZZI, P.C.; SPEARING, A.J.S.; JESSU, K.V.; SINGH, P. and HAWKER, R. Combined load ailu e
c i e ion o ock bol s in ha d ock mines. Mining Me allu gy & Explo a ion. 2021, ol. 38, pp. 427–432.
A ailable om: h ps://doi.o g/10.1007/s42461-020-00289-4.
[13] MOHAMMADI, M.; HOSSAINI, M.F. and BAGLOO, H. Rock bol suppo ing ac o : ock bol ing
capabili y o ock mass. Bulle in o Enginee ing Geology and he En i onmen . 2017, ol. 76, p.231–239.
A ailable om: h ps://doi.o g/10.1007/s10064-015-0785-y.
[14] FENG, S.J.; FU, W.D.; CHEN, H.X.; LI, H.X.; XIE, Y.L. e al. Field es s o mic o sc ew ancho piles
unde di e en loading condi ions a h ee soil si es. Bulle in o Enginee ing Geology and he En i onmen .
2021, ol. 80, pp.127–144. A ailable om: h ps://doi.o g/10.1007/s10064-020-01956-y.
[15] MITTAL, S. and MUKHERJEE, S. Ve ical Upli Capaci y o a G oup o Helical Sc ew Ancho s in Sand.
Indian Geo ech Jou nal. 2013, ol. 43, pp. 238–250. A ailable om: h ps://doi.o g/10.1007/s40098-013-
0055-5