scholarly journals Research on the Large Deformation Prediction Model and Supporting Measures of Soft Rock Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Junying Rao ◽  
Yonghu Tao ◽  
Peng Xiong ◽  
Chongxin Nie ◽  
Hao Peng ◽  
...  
Keyword(s):  
Large Deformation ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Maximum Displacement ◽  
Deformation Prediction ◽  
Significant Difference ◽  
Rock Tunnel ◽  
Surrounding Rock Deformation ◽  
Bolt Support

The weak surrounding rock has the characteristics of easy softening, poor integrity, low mechanical strength, etc., which makes it easy to induce different degrees of deformation and damage under excavation disturbance and then seriously affects the stability of the tunnel. Carrying out soft rock tunnel deformation prediction research and designing the supporting structure according to the predicted value is of great significance to engineering construction and design. Based on the grey theory, the large deformation of the vault, shoulder, and waist of the soft rock tunnel are predicted, and then the specific bolt support is designed in the maximum predicted value (Smax·R) area. The control effects of different bolts, spacing (d), length (L) on the maximum displacement (Smax·M), and maximum stress (σmax·M) the surrounding rock are analyzed by numerical simulation. Results show that the gray model has high prediction accuracy, the best prediction time is one week, and the maximum error is only 2.99%; with the decrease in d, resin bolt support has a significant supporting effect compared with mortar bolt support, with Smax.M and σmax·M reduced by 64.38% and 10.35%, respectively; as the L of bolt increases, compared with the mortar bolt support, the resin bolt support has a more obvious restraining effect on the surrounding rock deformation, and Smax·M and σmax·M are reduced by 28.20% and 10.00%, respectively; when 4.5 m < L < 6.0 m and 0.6 m < d < 0.7 m, resin bolt support should be adopted; in other ranges, mortar bolt support or resin bolt support has a less significant difference in controlling surrounding rock deformation.

Comparison and Analysis of Different Excavation Methods in Soft Rock-Extremely Soft Rock Tunnel

2012 ◽  
Vol 256-259 ◽  
pp. 1201-1205
Author(s):  
Xiang Dong Zhang ◽  
Peng Tao Zhao ◽  
Wen Jun Gu
Keyword(s):  
Soft Rock ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Maximum Difference ◽  
Tunnel Excavation ◽  
Comparison And Analysis ◽  
Rock Tunnel ◽  
Complex Geology ◽  
Surrounding Rock Deformation ◽  
Excavation Methods

In order to further study the law of surrounding rock deformation of soft rock-extremely soft rock double arch tunnel, resolve problem of tunnel excavation in complex geology conditions, based on project example, the central heading full section, central heading step and division method (three heading method) as research object, measured and simulated results were compared and analyzed, and used ANDIA software to do dynamic simulation. The results show that the characters of surrounding rock deformation are different with different excavation methods; Simulated and measured results are almost the same ,and the maximum difference has only 6%, reflecting simulated value has a certain reliability; The more the step numbers are excavated in soft rock-extremely soft rock tunnel, the smaller the area excavated is, the smaller the rock is disturbance, the smaller the surface subsidence and two state convergence value is, more be able to meet construction requirements; Compared with the other two methods, division method is more to reduce the deformation in the surrounding rock with class of V.

Application of Long Anchor in Support Optimization of Soft Rock Tunnel

2013 ◽  
Vol 368-370 ◽  
pp. 1614-1624
Author(s):  
Yang Sun ◽  
Jian Ping Chen ◽  
Wei Zheng ◽  
Li Yu
Keyword(s):  
Soft Rock ◽  
Surrounding Rock ◽  
Parameters Optimization ◽  
In Situ Monitoring ◽  
Rock Deformation ◽  
New Thought ◽  
Supporting Structure ◽  
Rock Tunnel ◽  
Surrounding Rock Deformation

supporting structure parameters optimization is always a research focus in soft rock tunnel. Combined with Youfangping tunnel in Guzhu highway, the scheme of long anchor supporting has been provided. Usually the length of systematic anchor was determined according to experience, it often not reasonable. In order to determine the length of anchor, in-situ wave velocity test and theoretical calculation was used, and with the consideration of safety and economy, the length of anchor was determined as 4.5m finally; At the same time combined with in-situ monitoring measurement, two test sections was selected, and with the comparison of the designed supporting scheme and the original strong supporting scheme, it can be found that: no matter from the sight of surrounding rock deformation, stress applied on surrounding rock or force pattern of supporting structure, the supporting form by lengthening anchor can control surrounding rock deformation more effectively, can improve the bearing capacity of surrounding rock fully and improve the effect of supporting structure. And the supporting scheme of long anchor was more reasonable than the strong supporting scheme. This long anchor supporting scheme can provided new thought to supporting design of soft rock tunnel in Guzhu highway.

scholarly journals Analysis on Loose Circle of Surrounding Rock of Large Deformation Soft-Rock Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Rui Wang ◽  
Yiyuan Liu ◽  
Xianghui Deng ◽  
Yu Zhang ◽  
Xiaodong Huang ◽  
...  
Keyword(s):  
Large Deformation ◽  
Theoretical Calculations ◽  
Rapid Development ◽  
Field Tests ◽  
Soft Rock ◽  
Strength Criterion ◽  
Surrounding Rock ◽  
Distribution Law ◽  
Geological Conditions ◽  
Rock Tunnel

With the rapid development of tunnel construction in China, deep buried and long tunnel projects are emerging in areas with complex engineering geological conditions and harsh environment, and thus large deformation of tunnels under conditions of high in situ stress and soft rock becomes increasingly prominent and endangers engineering safety. Therefore, it is of great significance to control the deformation and improve the stability of surrounding rock by analyzing the thickness and distribution law of loose circle according to the unique mechanical properties and failure mechanism of surrounding rock of large deformation soft-rock tunnel. Based on unified strength theory, this paper deduces the radius calculation formula of the loose circle by considering the influence of intermediate principal stress. Furthermore, the theoretical calculations and field tests of the loose circle in the typical sections of grade II and III deformation of Yuntunbao tunnel are carried out, and the thickness and distribution law of loose circle of surrounding rock of large deformation soft-rock tunnel is revealed. The results show that the formula based on the unified strength criterion is applicable for a large deformation tunnel in soft rock.

Analysis of Surrounding Rock Deformation Behavior and Supporting Measures in High-Level Strata Pressure Tunnel

2012 ◽  
Vol 170-173 ◽  
pp. 1629-1633
Author(s):  
Li Wu ◽  
Qing Jun Zuo ◽  
Li Shi ◽  
Zhong Le Lu
Keyword(s):  
Large Deformation ◽  
Deformation Behavior ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Deformation Characteristics ◽  
Geological Investigation ◽  
Pressure Tunnel ◽  
High Level ◽  
Surrounding Rock Deformation

According to geological investigation and monitoring results, this paper analyzed the reasons for large deformation in Baozhen Tunnel, discussed the deformation characteristics and presented the corresponding supporting measures.

scholarly journals In Situ Needle Penetration Test and Its Application in a Sericite Schist Railway Tunnel, Southwest of China

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Jiaxing Dong ◽  
Runxue Yang ◽  
Chenggang Guo ◽  
Meiqian Wang ◽  
Yonghong Wu ◽  
...  
Keyword(s):  
Large Deformation ◽  
Soft Rock ◽  
Reference Value ◽  
Surrounding Rock ◽  
Mechanical Parameters ◽  
Penetration Index ◽  
Needle Penetration ◽  
Joint Direction ◽  
Rock Tunnel

Abstract The sericite schist is a typical metamorphic soft rock. Large deformation of surrounding rock often occurs in the construction of a tunnel in this stratum. Due to the broken rock mass structure and poor mechanical strength in Baishitou tunnel project of Dalin line of Southwest railway, it is impossible to prepare standard samples for a traditional rock mechanical test. Therefore, we chose penetrometer (SH-70) for an in situ test. Firstly, we monitored the deformation of typical sections and analyzed the characteristics of large deformation of soft rock in the tunnel. Secondly, we tested the needle penetration index of fresh excavation face and side wall. Then, we estimated some mechanical parameters of sericite schist by a needle penetrometer and Hoek-brown criterion and discussed the acquisition of mechanical parameters of soft rock. The results show the following: (1) the characteristics of extrusion rock tunnel are summarized as large deformation, fast deformation rate, and obvious construction disturbance. (2) The reference value of penetration index of sericite schist (the vertical joint direction) is 3.90~7.77 N/mm, and the parallel joint direction is 1.27~2.99 N/mm. (3) The uniaxial compressive strength estimated by a penetrometer is 0.78~8.53 MPa, and the strength of the surrounding rock is negatively correlated with the amount of deformation. Therefore, it can be considered that the insufficient strength of surrounding rock is the fundamental reason for large deformation. (4) The reference value of cohesion of sericite schist estimated by a penetrometer is 0.203 MPa, and the reference value of internal friction angle is 18.224°. Compared with the common estimation methods, the penetrometer is more convenient and economical, which can provide a new idea for obtaining the mechanical parameters of sericite schist soft rock tunnel.

Surrounding Rock Deformation Properties and Control Technique for Roadway along Goaf in Soft Rock

2014 ◽  
Vol 1010-1012 ◽  
pp. 1482-1486 ◽  
Author(s):  
Ming Yang ◽  
Xin Zhu Hua ◽  
Deng Hong Chen
Keyword(s):  
Soft Rock ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Control Technique ◽  
Deformation Properties ◽  
Economical Benefit ◽  
Practical Engineering ◽  
Supporting Effect ◽  
And Control ◽  
Surrounding Rock Deformation

Deformation of roadway driving along goaf was very serious during mining in Qidong coal Mine.This paper took the roadway as the engineering background, firstly, numerical simulation of the roadway has been made by FLAC3D,then its surrounding rock deformation properties and stress distribution were analyzed,the reinforcement technology was proposed during mining, lastly, the deformation around roadway during mining was observed and analyzed. The practical engineering shows that : the combined supporting of bolting-shotcreting-grouting can effectively control the deformation around roadway, the supporting effect is good , and better social and economical benefit have been gotten.

Significant Analysis of Soft Rock Tunnel Disaster-Causing Factors Based on Orthogonal Test

2012 ◽  
Vol 594-597 ◽  
pp. 1331-1337
Author(s):  
Jian Ping Chen ◽  
Ying Xu ◽  
Chang Qun Zuo ◽  
Yi Yi
Keyword(s):  
Large Deformation ◽  
Pressure Coefficient ◽  
Soft Rock ◽  
Tectonic Stress ◽  
Surrounding Rock ◽  
Joint Spacing ◽  
Dependent Relationship ◽  
Side Pressure ◽  
Dependence Relationship ◽  
Rock Tunnel

The impacting effect of lithological features, tectonic stress, the mechanical parameters, structure surface contrasts were comparative analysis, to explore the effect from mentioned factors to surrounding rock-lining in schist tunnel. In order to make sure the dependence relationship of large deformation with these factors, the significant and interaction on large deformation in rock-mess and lining mechanical mechanism were studied according to the experiment data and statistics theory. The result shows that elastic modulus E, side pressure coefficient λ, and joint spacing S have obvious influence on the mechanical properties of surrounding rock-lining, and there is interaction among them. Furthermore, the influence of the interaction between S and λ to rock-lining is found to be significant, and there is an obviously dependent relationship between anchor failure and joints spacing. Therefore, when discussing the reduction measures to avoid the large deformation, the most appropriate method is to study it in overall factors and with the interaction.

Judgement Method for Surrounding Rock Stability of Guanjiao Tunnel Based on Catastrophe Theory

2011 ◽  
Vol 90-93 ◽  
pp. 2307-2312 ◽  
Author(s):  
Wen Jiang Li ◽  
Su Min Zhang ◽  
Xian Min Han
Keyword(s):  
Plastic Strain ◽  
Catastrophe Theory ◽  
Soft Rock ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Engineering Practice ◽  
Stability Of Surrounding Rock ◽  
The Stability ◽  
Rock Tunnel

The stability judgement of surrounding rock is one of the key jobs in tunnel engineering. Taking the Erlongdong fault bundle section of Guanjiao Tunnel as the background, the stability of surrounding rock during construction of soft rock tunnel was discussed preliminarily. Based on plastic strain catastrophe theory, and combining numerical results and in-situ data, the limit displacements for stability of surrounding rock were analyzed and obtained corresponding to the in-situ monitoring technology. It shows that the limit displacements obtained corresponds to engineering practice primarily. The plastic strain catastrophe theory under unloading condition provides new thought for ground stability of deep soft rock tunnel and can be good guidance and valuable reference to construction decision making and deformation managing of similar tunnels.

Sign in / Sign up

Export Citation Format

Share Document