In contrast, the imperforate film mulching method is a way to cover the topsoil with the film fixed by compacted soil on its ends when the crop is planted beside the film. 地膜覆蓋無(wú)孔種植法，用地膜平鋪于表土，邊沿用土壓緊封閉，將莊稼種在地膜旁邊，膜下土壤中的水分和熱量不易散失，卻容易吸收外界水分，因此，莊稼增產(chǎn)不比傳統覆蓋法少。
The calculation principle of earth pressure using principal stress arching is proposed. 給出了用主應力拱應力分析計算土壓力的基本原理。
During the process of computation the traditional Ranken's earth pressure theory and that of Coulomb's were reasonably simplified. 設計計算時(shí)，對傳統的朗金土壓力和庫侖土壓力理論進(jìn)行了合理的簡(jiǎn)化。
