METHOD FOR COAGULATING EARTH AND SAND AND MUD SHIELD METHOD USING THE SAME

PURPOSE:To carry a great amount of mud out of a drift and transfer it efficiency by injecting into earth and sand mud coagulation agents containing acrylic water soluble polymer having specific molecular weight, silty clay and water at a predetermined ratio so that they are kneaded and formed into a coagulated state. CONSTITUTION:Silty clay is dispersed in water to form a clay suspension, into which acrylic water soluble polymer is added and mixed to prepare mud coagulation agent, wherein the weight ratio of silty clay to water is 0.1-1:1; the weight ratio of acrylic water soluble polymer to silty clay 0.001-0.1:1. Said agent is injected into a chamber 2 formed at the rear of a partition wall 11 provided at the front of a cutting face 15 and kneaded with excavated earth and sand which is excavated at the cutting face 15. In this manner, mud having appropriate fluidity, in a coagulated state, is produced. As a result, stability of earth and sand of the cutting face 15 can be maintained, so that the earth and sand can smoothly be discharged by means of a screw conveyor 13 and surplus soil can be handled easily.