Nghiên cứu sự làm việc của nhóm cọc ngắn trên nền địa chất yếu có cát san lấp sử dụng mô hình vật lý thu nhỏ Schneebeli

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Tác giả: SỸ HÙNG NGUYỄN, TIẾN SĨ NGUYỄN, THANH VŨ PHAN, THỊ PHƯƠNG HUYỀN TRẦN

Ngôn ngữ: vie

Ký hiệu phân loại:

Thông tin xuất bản: Tạp chí Xây dựng, 2023

Mô tả vật lý: tr.107

Bộ sưu tập: Metadata

ID: 341480

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Bài báo này tập trung nghiên cứu ứng xử của nhóm cọc trên nền đất yếu có cát san lấp trên mô hình thu nhỏ 2D sử dụng đất tương tự của Schneebeli. Đồng bằng sông Cưu Long có nhiều khu vực xây dựng nhà thấp tầng trên nền đất yếu, với lớp cát san lấp dày từ 2 - 5m. Phương án sử dụng cọc nhỏ (tiết diện nhỏ hơn 30×30 cm) và ngắn (chiều dài ngắn hơn 5m) đóng trong lớp đất cát có thể áp dụng cho nhà thấp tầng với điều kiện địa chất như trên. Trong mô hình thu nhỏ, chúng tôi sử dụng đất tương tự Schneebeli để thay cho lớp cát san lấp và xốp thay cho lớp đất sét yếu. Các cọc bê tông cốt thép ngắn được thay thế bằng các thanh thép có tiết diện vuông. Thí nghiệm tải thẳng đứng được thực hiện trên các nhóm cọc. Các thông số thí nghiệm được thay đổi trong chương trình thí nghiệm bao gồm khoảng cách cọc s, khoảng cách từ mũi cọc đến ranh giới hai lớp đất H, trong khi bề dày các lớp đất không đổi. Trong trường hợp nhóm cọc không có đài móng, khi khoảng cách cọc s không đổi và khoảng cách từ mũi cọc đến ranh giới hai lớp đất H giảm thì diện tích đất biến dạng dưới mũi cọc giảm. Trong trường hợp H cố định và s tăng thì sự phá hoại của đất dưới mũi cọc ngày càng trở nên cục bộ. Khi nhóm cọc có đài móng sức chịu tải của nhóm cọc tăng lên, tuy nhiên biến dạng thẳng đứng của lớp xốp cũng tăng lên theo cả phương thẳng đứng và phương ngang. Từ khóa: Vật liệu Schneebeli
nhóm cọc
gia tải thẳng đứng
cát san lấp
đất yếu.This paper focuses on the behavior of pile groups on soft ground with sand leveling on a 2D small-scale model using the analog soil of Schneebeli. The Mekong Delta has many areas where low-rise buildings are built on soft ground with a sand backfill layer of thickness between 2 - 5m. The option of using small (section smaller than 30×30 cm) and short (length shorter than 5m) piles driven into the sandy soil layer can be applied to low-rise buildings with the above geological conditions. In the small-scale model, we use Schneebeli analog soil to replace the leveling sand and foam instead of the weak clay layer. Short reinforced concrete piles are replaced by steel bars with a square cross-section. The vertical loading tests were carried out on 3-piles groups. Experimental parameters are changed in the test program, including the pile spacing s, and the distance from the tip of the pile to the boundary of the two soils, H, whereas the thickness of the soil layers is unchanged. If the pile group has no footing when the pile spacing s is unchanged, and the distance from the tip of the pile to the boundary of the two soils, H decreases, the deformed soil area under the pile tip decreases. If H is fixed and s is increased, soil failure under the pile tips becomes more and more localized. When the pile group has a footing, the bearing capacity of the pile group increases. As a result, however, the vertical deformation of the foam layer also increases in both the vertical and horizontal directions. Keywords: Schneebeli soil analog
pile group
vertical loading test
sand leveling
weak soil.

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