直撑 - 引用次数：1参考来源 - 考虑坑壁位移和土压力方向的直撑力学特性 Mechanical characteristics of straight brace considering displacement of foundation pit and direction of earth pressure
Grab the seat of your chair to brace yourself and extend your legs straight out in front of you so they are parallel to the floor, then release slowly to work out your muscles.