For a soft rock tunnel under high stress in jointed and swell soft rock(HJS), two construction schemes pilot-tunneling enlarging excavation and step-by-step excavation were optimized using FLAC2 D, and the deformation...For a soft rock tunnel under high stress in jointed and swell soft rock(HJS), two construction schemes pilot-tunneling enlarging excavation and step-by-step excavation were optimized using FLAC2 D, and the deformation effects of the two construction schemes were verified by field tests. Based on engineering geological investigation and mechanical analysis of large deformations, the complex deformation mechanisms of stress expansion and structural deformation of the soft rock tunnel were confirmed,and support countermeasures from the complex deformation mechanism converted to a single type were proposed, and the support parameters were optimized by field tests. These technologies were proved by engineering practice, which produced significant technical and economic benefits.展开更多
This paper presents a numerical study on the pullout behavior of the rockbolt grouted system. Among the complicated failure modes of the rockbolt grouted system, the crack of the grout is concerned here. A trilinear c...This paper presents a numerical study on the pullout behavior of the rockbolt grouted system. Among the complicated failure modes of the rockbolt grouted system, the crack of the grout is concerned here. A trilinear cohesive zone model(CZM) is used to simulate the interfacial behavior of rockbolt–grout interface;and a plastic damaged model is adopted for the grout materials. The feasibility of the numerical method is verified by comparing the calculated results with the test observations. The numerical results indicate that two types of cracks of the grout materials can be identified as the inclined crack and the horizontal crack. The inclined crack forms firstly and then the horizontal crack. Both cracks can reduce the interfacial shear stress and thus reduce the load transfer efficiency. Further analysis indicates that the crack of the gout material can induce the obvious drops of load capacity, which is not a safe failure mode. This study leads to a better understanding of the mechanism for rockbolt grouted system.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51474188, 51074140 and 51310105020)the Natural Science Foundation of Hebei Province (No. E2014203012)the Program for Taihang Scholars
文摘For a soft rock tunnel under high stress in jointed and swell soft rock(HJS), two construction schemes pilot-tunneling enlarging excavation and step-by-step excavation were optimized using FLAC2 D, and the deformation effects of the two construction schemes were verified by field tests. Based on engineering geological investigation and mechanical analysis of large deformations, the complex deformation mechanisms of stress expansion and structural deformation of the soft rock tunnel were confirmed,and support countermeasures from the complex deformation mechanism converted to a single type were proposed, and the support parameters were optimized by field tests. These technologies were proved by engineering practice, which produced significant technical and economic benefits.
基金financially supported by the National Natural Science Fund of China (Nos. 51304067 and 51104057)the Fund of Opening Laboratory for Deep Mine Construction, Henan Polytechnic University (No. 2012KF-01)the Education Department of Henan Province (No. 13A440311)
文摘This paper presents a numerical study on the pullout behavior of the rockbolt grouted system. Among the complicated failure modes of the rockbolt grouted system, the crack of the grout is concerned here. A trilinear cohesive zone model(CZM) is used to simulate the interfacial behavior of rockbolt–grout interface;and a plastic damaged model is adopted for the grout materials. The feasibility of the numerical method is verified by comparing the calculated results with the test observations. The numerical results indicate that two types of cracks of the grout materials can be identified as the inclined crack and the horizontal crack. The inclined crack forms firstly and then the horizontal crack. Both cracks can reduce the interfacial shear stress and thus reduce the load transfer efficiency. Further analysis indicates that the crack of the gout material can induce the obvious drops of load capacity, which is not a safe failure mode. This study leads to a better understanding of the mechanism for rockbolt grouted system.
