A Unified Solution for Surrounding Rock of Roadway Considering Seepage, Dilatancy, Strain-Softening and Intermediate Principal Stress

Abstract

The analytic solution for surrounding rock of roadway is of significance for stability analysis and roadway support. However, analytical solution for surrounding rock of roadway which took influences of water seepage, strain softening, dilatancy and intermediate principal stress all into account did not receive much reporting. To promote research in this aspect, a mechanical model simultaneously considering water seepage, strain softening, rock dilatancy, and intermediate principal stress was established based on porous elastoplastic mechanics, and then unified analytical solution for surrounding rock of roadway was obtained. Based on an example, influences of water seepage, strain softening, rock dilatancy, residual cohesion and intermediate principal stress on surrounding rock of roadway were thoroughly investigated using single factor analysis. The obtained results are as follows: radii of plastic zones and surface displacement of roadway would increase exponentially with water pressure increasing and their magnitudes are greater than corresponding values without water seepage considered; with softening modulus increasing, peak circumferential stress location would slightly shift to deeper surrounding rock, while broken zone radius and surface displacement of roadway would increase in a decay velocity; rock dilatancy has little effect on peak circumferential stress and plastic softening zone radius, while broken zone radius and surface displacement of roadway increase linearly with dilatancy coefficient α1 increasing indicating their magnitudes are overestimated if associated flow rule is adopted; with weighted coefficient increasing, stress components in plastic zones at the same distance from roadway center would increase, while radii of two plastic zones and surface displacement of roadway are reduced, i.e., self-bearing capacity of rock is enhanced considering intermediate principal stress effect compared to Mohr–Coulomb criterion; with residual cohesion increasing, peak circumferential stress remains unchanged, while stress components in plastic zones at the same distance from roadway center would increase and radii of two plastic zones decrease significantly. The above results implicated that water seepage effect should be carefully considered for roadway stability under groundwater environment; strain-softening and flow rule of rock should be reasonably analyzed and chosen to accurately predict surface displacement and broken zone radius of roadway; rock bolt length should be increased with softening modulus increasing, while it can be decreased with intermediate principal stress effect considered; grouting measure is an effective measure to improve roadway stability. In short, the research provides a theoretical basis and some practical engineering implication for roadway support.

Fracture Closure Empirical Model and Theoretical Damage Model of Rock under Compression

“…From a general view on the typical rock failure process, a complete axial stress–strain curve includes the pre-peak curve and the post-peak curve [ 44 , 45 ], as shown in Figure 3 . The pre-peak curve can further be divided into four stages by fracture development, simultaneously gaining four stress thresholds [ 46 , 47 , 48 ]: fracture closure stress σ cc , fracture initiation stress σ ci , rock damage stress σ cd , and peak stress σ p .…”

Apparent Deterioration Law and Shear Failure Mode of Rock–Mortar Interface Based on Topography-Sensing Technology

“…As shown in Figure 6 , the rock–mortar interface samples formed by three types of rocks and mortar are prepared [ 58 , 59 ]. The three rocks are, respectively, malmstone, red sandstone, and blue sandstone, which are denoted as A, B, and C. Firstly, the natural irregular interfaces are obtained by direct shear tests on the complete rock samples (cubic rock with the length of 70 mm), and the basic mechanical parameters of the three rocks are measured as shown in Table 1 .…”

Experimental Study on Shear Behavior of Rock Composite Material under Normal Unloading Conditions

“…In addition, due to the isolation of rock samples, their stress–strain state is complex, so it is difficult to take the stress–strain state as the only instability criterion [ 36 , 37 ]. Therefore, analysis of energy and stress–strain state should be combined to better reveal the failure characteristics of rock mass [ 38 , 39 ].…”