本研究目的在瞭解砂土中添加細菌所產生的生物性膠結，探討生物性膠結對砂土的滲透性與剪力強度的改變成度，以期能作為土壤改良的方法。試體準備過程中，將假單胞桿菌注入土壤以產生尿素酶，其中尿素酶轉化為尿素並跟水反應產生碳酸鹽類，引致碳酸鈣在砂質土壤中沉澱。透過碳酸鈣沉澱可以填補砂土之間的縫隙和增加砂土顆粒的鍵結力，提高土壤的剪力強度。試驗中，使用尚未滅菌的土壤在室外進行實驗，其目的在模擬於現地場址中利用生物性膠結改良工法之實際情況，將微生物引致碳酸鈣沉澱方法應用於地盤改良為大地工程領域新的分支，利用定水頭試驗、直接剪力試驗、加州承載比試驗和ESEM (環境掃描電子顯微鏡) 觀測其物理及化學性質變化，經由試驗結果評估該工法於現地施作之可行性。;In this research, the authors tried to analyze the addition of bacterial producer of biological cement on sandy soil to increase its stability. It is expected that the biological cement of bacteria can enhance soil stability by reducing its permeability and increase its shear strength. Pseudomonas sp was injected into the soil to produce urease enzyme, which converts urea that reacted with water become ammonium and carbonate, causing calcite precipitation. Soil stability can be improved by the production of pore-filling materials and particle-binding materials through the calcite precipitation process. This method will be applied to sandy soil by modeling the soil in situ where the soil is non-sterilized, placed outside the room, also exposed to sunlight and air humidity. The aim of these applications is to improve the mechanical properties of soil that it will be more suitable for construction or environmental purposes. This is a new branch of geotechnical engineering that deals with the applications of biological microorganism methods to geological materials used in engineering. After bacterial inoculation, the permeability of sand samples will be tested with constant head test, shear strength with direct shear test, compaction with California Bearing Ratio test, and ESEM (Environmental Scanning Electron Microscopy) test.
