Large Deformation Characteristics of Surrounding Rock and Support Technology of Shallow-Buried Soft Rock Roadway: A Case Study

Abstract

The coal resources in the coal-rich area of western China are mostly located in the late diagenetic Cretaceous and Jurassic strata. In this paper, a study on the support of soft rock roadways was carried out in the background of the soft rock track roadway in the Jiebangou coal mine. The field investigation showed that the surrounding rocks of the roadway were weak, soft, and broken, and the surrounding rocks were cemented, with the roadway local deformation exceeding 1 m. The borehole television results showed that the surrounding rocks were mainly weak sandy mudstone and yellow mudstone. The average uniaxial compressive strength of the surrounding rock was 15.49 MPa. The roadway is a shallow buried soft rock roadway; site investigation revealed that the original U-shaped steel shed had an extremely low resistance to slip, the filling body behind the U-shaped steel shed fell off, the interaction between the U-shaped steel shed and the surrounding rock was poor, the U-shaped steel shed could not provide sufficient timely support resistance, and the bearing capacity of the U-shaped steel shed was far from consideration. The floor was not effectively supported. The floor had different degrees of the bottom drum, and frequent undercover caused new stress disturbances, which loosened the bottom corners of both rock types and made the shed legs move continuously inward, reducing the bearing capacity and actual support resistance of the bracket. Numerical calculations were performed to study the deformation characteristics of the surrounding rock of the tunnel and the yielding damage characteristics of the brace. The results showed that the current U-shack support strength was insufficient, the two sides were deformed by 950 mm, the bottom of the roadway bulged by 540 mm, and the surrounding rock was mainly shear damaged. The fall of the filler behind the shed caused damage to the U-shaped steel shed spire. Through site investigation results and numerical calculations, the deformation and damage characteristics of the soft rock roadway and its damage causes were analyzed, and the support technology system of ‘strengthening support for weak structural parts’ was proposed. This improved the mechanical properties of the weak structural support body, the stress state of the local surrounding rock, and the bearing capacity of the support structure, and effectively controlled the deformation, damage, and instability of the surrounding rock of the roadway, and deformation, damage, and destabilization of the roadway, thereby achieving overall stability for the surrounding rock of the roadway.

Research on Double-Layer Support Control for Large Deformation of Weak Surrounding Rock in Xiejiapo Tunnel

“…Ref. [19] used FLAC 3D software in simulating tunnel excavation and analyzing the mechanism of rock deformation and failure. They proposed a number of joint, multi-layer support measures that limited surrounding rock deformations effectively.…”

The Failure Law and Combined Support Technology of Roadways with Weak Surrounding Rock in Deep Wells

“…Wu et al [8] pointed out that the main reason for the tunnel's serious damage is that the surrounding rock's rheological deformation intensifies the crack propagation inside the rock. Through numerical simulation, Zhu et al [9] believed that when the rock mass strength is low, the surrounding rock failure is mainly shear damage, and tensile damage is mainly concentrated at the bottom of the tunnel. In addition, Zhang [10] divided the bearing structure into soft and weak mudstone roadway surrounding rock and proposed the control concept of effective anchoring of anchor rods and anchor cables.…”

Study on the Stress Distribution and Stability Control of Surrounding Rock of Reserved Roadway with Hard Roof

“…Due to the variability of surrounding rock properties, quarry stress, and roadway section size, the mechanism of roadway deformation and failure is diverse and complex, resulting in different methods and countermeasures for roadway support [16]. Different roadway support methods also have different effects on the sustainable development of coal mines.…”