CASING FOR EXCAVATION AND GROUND IMPROVEMENT METHOD

PROBLEM TO BE SOLVED: To provide a casing for excavation and a ground improvement method that allow drilling for measurement to be done for clarifying ground conditions at an even higher accuracy, and then may be used as a guide for inserting an outer pipe used in injection of chemicals, etc.SOLUTION: A casing 2 has a detachable body 5 detachably installed inside a tip part of a tubular body 3, and a resistance plate 8 installed by exposing a front surface having a groove 8a formed on an opening edge on the tip side of the tubular body 3, the tubular body having a bit 4a along the tip peripheral part. A ground is drilled using the casing 2 for measurement. Then, an outer pipe 10 is inserted into the casing 2 buried in the ground, and a pressing part 7 is pressed by the tip to release the fixed state between the detachable body 5 and the tubular body 3. The casing 2 is pulled out above the ground while leaving the detachable body 5 and the outer pipe 10 buried in the ground. Furthermore, chemical solution C is injected into the ground from an outlet 10a on a peripheral wall of the outer pipe 10, the chemical solution having been fed through an inner tube 11 for injection inserted in the outer pipe 10.SELECTED DRAWING: Figure 5 【課題】地盤の状態をより高精度で把握できる計測ボーリングを行なえるとともに、その後、薬液等の注入するための外管を挿入させるガイドとして利用できる掘削用ケーシングおよび地盤改良方法を提供する。【解決手段】先端周縁部にビット４ａを有する筒状体３の先端部内側に着脱体５を着脱自在に設け、筒状体３の先端側開口端に溝８ａを有する前面を露出させて抵抗板８を配置したケーシング２を用いて地盤を掘削して計測ボーリングを実施後、地盤に埋設したままのケーシング２に外管１０を挿入してその先端部で押圧部７を押圧して着脱体５の筒状体３との固定を解除させ、ケーシング２を地上に引き抜いて着脱体５および外管１０を地盤に埋設した状態で、外管１０に挿入した注入用内管１１を通じて供給した薬液Ｃを外管１０の周壁の吐出口１０ａから地盤に注入する。【選択図】図５