②荷载计算a．墙顶荷载：垂直力Nb,水平力Vb和弯矩Mb,结构自重标准值所产生,b．侧压力计算Ei=0．5γwHi+Δhwi,γw为土中水容量,即γww=(γ-1)；如在水位以上,则γ=0．5：为土压力侧压系数,按静止土压力计算,不应按tg2(45°-Φ/2)计算；c．水压力：hw(水位差),这里要注意两点：土压力应按静土压力计算,即e=0．5γh；因为地下室墙顶位移为0,一般侧压系数为1-sinΦ或0．5。但当墙(桩)为悬臂时,土压力按主动土压力计算,即e=rhtz2(45°-Φ/2)。如有地下水时,一定要水土分开计算,否则不安全。③内力及配筋汁算a．配筋计算：根据以上分析,边墙构件应属偏心受压构件,但目前在设计时多是按纯弯构件来计算和配筋,所以配筋偏于保守和浪费,更有的是按裂缝宽度来验算．而且裂缝宽度还是按二类环境0．2mm来控制,结果是墙厚、筋多,耗钢量急剧上升。b．关于裂缝宽度的验算目前在板的计算和配筋中,多是裂缝宽度起控制因素,这里需注意：第一、裂缝的控制等级及允许最大裂缝宽的标准是怎样定的,目前设计者多认为,只要是地下室外墙,其环境类别就是二类,则根据规范表3．3．4与其对应的裂缝等级就是三级,控制裂缝的宽度为0．2mm,墙薄不了,配筋也少不了。但此标准定的是否合适,值得探讨。因为地下室外墙已设置了外包防水层,根据美国规范,算是有保护的结构,与完全暴露于土或水中的结构截然不同,从实际来讲,应属一类的环境。至于将来防水层破坏了怎么办?问题不能如此假设。据记载,莫斯科地铁发现40—50年前做的卷材防水,至今仍完好无损,所以现在做的防水层,特别是埋于地下的防水层,不一定有什么问题,所以其环境类别可定为一类,并符合表3_3．4注2的条件,裂缝宽度可定为0．4mm。第二、目前计算裂缝宽度的公式,是根据一个单跨简支粱的试验而来,对一些超静定的连续梁或多跨连续的双向板等均不适用,所以现在算出的裂缝宽度,无论是按规范公式手算或程序电算,对于一些超静定的结构来讲其结果 ② load calculation a. Wall load: vertical force Nb, horizontal force Vb and bending moment Mb, the standard weight of the structure, b. Side pressure calculation Ei = 0.5γwHi + Δhwi, γw is the soil water capacity, that γww = (γ-1); If above the water level, then γ = 0.5: for earth pressure side pressure coefficient, Calculated, should not be calculated tg2 (45 ° -Φ / 2); c. Water pressure: hw (water level difference), we should pay attention to two points here: earth pressure should be calculated according to earth pressure, ie e = 0.5γh; because the displacement of wall basement is 0, the general lateral pressure coefficient is 1-sinΦ or 0. 5. However, when the wall (pile) is cantilever, earth pressure is calculated as active earth pressure, ie e = rhtz2 (45 ° -Φ / 2). If there is groundwater, we must separate the soil and water, otherwise it is not safe. ③ internal force and reinforcement juice count a. Reinforcement calculation: According to the above analysis, the side wall member should be eccentric compression member, but at present, the design is mostly based on pure bending components to calculate and reinforcement, so tend to be conservative and waste reinforcement, and more according to the crack width Check. And the crack width is still controlled by 0.2mm in the second type of environment, the result is a wall thickness, tendons, and consumption of steel increased dramatically. b. The calculation of the crack width Currently in the calculation of the plate and reinforcement, the crack width is the most control factors, should be noted here: First, the crack control level and the maximum allowable crack width is how the standard set, the current number of designers That as long as the basement wall, its environmental category is the second category, according to the specifications of Table 3.3.4 corresponding to the level of cracks is three, the width of the control cracks 0.2mm, the wall can not thin, reinforcement and ultimately . However, whether this standard is suitable or not is worth discussing. Because the outer wall of the basement has been provided with a waterproof outer layer, according to the United States norms, be regarded as protected structure, completely different from the soil or water structure, in fact, should belong to a class of environment. As for the future waterproof layer destroyed how to do? The problem can not be so assumed. According to records, Moscow Metro found 40-50 years ago to do the membrane waterproof, still intact, so now made waterproof layer, especially in the underground waterproof layer, there is not necessarily any problem, so the environment may be set For a class, and meet the conditions of Table 3_3.4 Note 2, the crack width can be set to 0.4mm. Second, the current formula for calculating the crack width is based on the test of a single-span simply-supported beam and does not apply to some statically indeterminate continuous beams or multi-span continuous two-way panels. Therefore, the calculated crack width, Whether it is calculated according to the standard formula or calculated by the program, the result of some statically indeterminate structure