The technology for gob-side entry retaining in steep coal seams is still in the development stage. The

analysis results of the caving structure of main roof, low influence of gateway’s stability because of long

filling distance and weak dynamic effect of the gateway, and the low stress redistribution environment

indicate that using this technology in steep coal seams has significant advantages. Moreover, to reinforce

the waste rock and the soft floor and to better guard against the impact of the waste rock during natural

filling, a rock blocking device and grouting reinforcement method were invented, and theoretical calculations

result show that the blocking device has high safety factor. In addition, we also developed a set of

hydraulic support devices for use in the strengthening support zone. Furthermore, because the retaining

gateway was a systematic project, the selection of the size and shape of the gateway cross section and its

support method during the initial driving stage is a key step. Thus, first, a section the size of bottom width

and roof height of a new gateway was determined to meet any related requirements. Then, according

to the cross sections of 75 statistical gateways and the support technique, it chosen a trapezoidal cross

section when the dip of the coal seam is 35° < α ≤ 45°, a special and an inclined arch cross section when

45° < α ≤ 55°. Eventually, a support system of bolts and cables combined with steel mesh and steel belts

was provided. The support system used optimized material and improved parameters, can enhanced the

self-bearing ability of the surrounding coal and rock masses.

In this paper, based on the feasible method and sensors for the full-scale prestressed monitor, the novel optical fiber sensors and the traditional monitoring sensors will be set up into two prestressed concrete beams with the same geometrical dimensions, material properties, and construction conditions, etc. to investigate the working state of the novel sensors and obtain the evolution law of prestress loss of the prestressed feature component under the static load. The results show that the evolution law of prestress loss of the loaded beam under the condition of no damage state and initial crack is the same as the non-loaded one; however, the prestress loss increases with the increase of time under the situation with the limit crack. The total loss of the prestressed beam with the limit crack is 36.4% without damage. The prestress loss of the prestressed beam under the static load increase with the development of the crack (injury).