ผลกระทบจากการเปลี่ยนแปลงปริมาณความชื้นต่อกำลังรับน้ำหนักบรรทุกของชั้นดินบวมตัวในอำเภอแม่เมาะ จังหวัดลำปาง

Abstract

This study aims to investigate the heaving and bearing capacity of the expansive soil in Mae Moh district, Lampang province, Thailand, which reduces after swelling and saturating with water, by testing samples from a residential building with heaving and potentially settling problems. The study method involves examining the soil's bearing capacity from shear parameters: cohesion and internal friction angle obtained from direct shear tests on soil samples soaked in the shear box. The results show that in all cases, the soil stops swelling when moisture content increases by approximately 30 to 32%, with reduced cohesion and friction angles when initial moisture content is higher and dry density is lower, including lower normal stress. From the calculations of the bearing capacity using the test results, it is found that the bearing capacity significantly decreases when the initial dry density is less than 16 kN/m³, which is particularly dangerous for designing spread footing. Hence, testing the shear strength of soil under swelling conditions with increased moisture content is essential for designing foundation bases on expansive soil, as the strength could decrease by approximately 5-6 times naturally.