Subsidence deformation of abandoned goafs can induce cracking, distortion and even collapse of surface buildings (structures), and thus, subsidence deformation poses a great threat. Accurate detection of the abandoned goaf location and overburden morphology is an important prerequisite for stability evaluation and scientific management of surface buildings (structures), and effective detection methods are bottlenecks for accurate detection. Taking the abandoned goaf in the Tengzhou section of China’s Mu Shi expressway as an engineering example, step-by-step detection, traditional detection and combination methods are used to determine the location of the underlying abandoned goaf and overburden morphology. First, we conduct disaster investigation on the expressway and surface within the affected area of the abandoned goaf and initially determine the detection area. Then, according to the principle that the detection range can be examined step-by-step from large to small, the high-density resistivity method is used for detection, and the high-resolution seismic method is further selected to analyze the target area. Then, based on the results of the resistivity method, the position of the abandoned goaf is evaluated with the high-resolution seismic method, and the distributions of the overburden subsidence, the water-filled fractured zone and the caving zone (the three belts) are determined. Finally, boreholes are drilled deep into the bottom of the abandoned goaf at specific locations and the distributions of the abandoned goaf and three belts are verified and corrected with drilling data, acoustic detection and borehole TV imaging technology, thereby providing accurate data on abandoned goafs for highway stability evaluation.

The stable surrounding rock is the key to ensuring tunnel availability in weakly cemented strata. In recent years, the joint support scheme of “steel beam + anchor net rope + grouting” was proposed based on numerical analysis, laboratory tests, and field tests, which was efficient in the short term. However, the effect of time and environment on the support structure was neglected. The weakly cemented mudstone was sensitive to water, with disintegration soaking up water and consolidation losing water. In this paper, analogy-based remolded soil puts forward the structural restrengthening of damaged mudstone. It was believed that when the clay content of a rock mass exceeded the critical proportion, the restrengthened structure could be regained under certain conditions of consolidation stress and water content. On the one hand, the residual strength of broken mudstone can be improved; on the other hand, pores and cracks are filled with minerals, restraining further water absorption. The structural strengthening feasibility of damaged mudstone was verified based on the geological characteristics and microscopic and strength tests. It is found that restrengthening specimens form cementation on the contacts of broken blocks. The greater the consolidation stress and moisture content, the denser the structure and the higher the strength. The research contributes to supporting the construction of weakly cemented mudstone.