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有底测坑是观测作物需水量的主要设施。安徽滁县农科所新创的顶推法,施工程序是:在试验现场,将测坑底板和墙壁分两处(相距80厘米左右)浇筑,待混凝土养护期满达到一定强度后,将混凝土坑壁连同里面的土体一起顶推到底板上,最后再封闭底板与坑壁的接合缝。1/200亩(2.78×1.20米~2)、1.1米深的有底测坑,混凝土墙厚一般10厘米,底部25厘米,口面30厘米。为防止混凝土开裂破坏,要配置构造钢筋。施工中,首先在现场将用于测坑的土块开挖成粗模型(比实际模型大10～30厘米),然后小心地削裁成型。在离测坑80厘米左右,开挖底板位置。土方完成后,立模布筋浇筑200~#混凝土。因墙厚仅10厘米,只能用钢钎人工捣实。底板厚度10厘米,滤水层因承压,故采用30～40厘米厚。底板养护一周后,开始充填滤水的碎石、粗砂、细砂等材料,上面的透水混凝土板可用机砖
Bottom pits are the main facility for observing crop water requirements. Chu Chu County, Anhui Agricultural Institute of the new push law, the construction process is: at the test site, the test pit bottom wall and the wall at two points (about 80 cm apart) to be poured until concrete expiration reached a certain strength, the concrete Pit wall along with the soil inside the top push to the floor, and finally closed floor and pit wall joints. 1/200 acres (2.78 × 1.20 m ~ 2), 1.1 meters deep bottom of the pit, the concrete wall thickness of 10 cm, 25 cm at the bottom, mouth 30 cm. To prevent concrete cracking damage, to configure the structure of steel. During the construction, the soil block used for measuring the pit should be excavated into a rough model (10-30 cm larger than the actual model) at the scene and carefully cut and shaped. About 80 centimeters from the test pit, excavation floor position. After the completion of earthwork, vertical reinforcement cloth pouring 200 ~ # concrete. Due to the wall thickness of only 10 cm, can only be manually tamped with steel drill. Floor thickness of 10 cm, due to pressure drainage layer, it uses 30 to 40 cm thick. One week after the floor conservation, began to fill the gravel water, coarse sand, fine sand and other materials, the above perforated concrete slabs available machine brick