Key words: soil mechanics; Teaching practice; teaching method
China Library ClassificationNo.: G642.0 Document ID: A DocumentNo.:1673-291x (2012) 24-0275-02.
Soil mechanics takes soil as the research object, mainly teaching theoretical knowledge such as soil composition, physical properties, seepage in soil, stress in soil, deformation and strength of soil, and engineering practical knowledge such as soil pressure, slope stability and foundation bearing capacity. Soil mechanics is gradually developed on the basis of a large number of theoretical derivation, experimental data and engineering practice experience, and is a basic course for many majors such as water conservancy, civil engineering, construction, transportation, port, geology and environmental engineering [1]. This course aims to cultivate students' ability to analyze engineering problems and conduct soil mechanics experiments. It is the knowledge base for students to learn the following courses (such as basic engineering, foundation treatment, foundation pit engineering, etc.). ) is of core significance to the construction of professional curriculum system and knowledge structure. It is the theoretical basis for improving students' professional basic ability, which is of great significance for consolidating the professional foundation.
However, due to the revision of professional training program, the adjustment of professional courses and the characteristics of soil mechanics course, the teaching status and teaching effect of soil mechanics in recent years are not optimistic. At the same time, the new orientation of applied and innovative training objectives also puts forward new requirements for soil mechanics teaching at this stage. Therefore, under this new situation and background, how to do well the teaching of soil mechanics, improve the teaching quality and realize the training goal is a problem worth thinking and exploring.
First, the characteristics of soil mechanics course
As the research object of soil mechanics, soil is an aggregate of broken minerals produced by long-term weathering of crustal rocks, with complex composition and strong temporal and spatial variability. Therefore, although soil mechanics is a branch of mechanics, it is not as rigorous as other branches of mechanics in terms of theoretical system logic and knowledge system. The basic concepts, basic theories and calculation formulas involved in the course are mostly derived from geotechnical tests or engineering practice experience, lacking strict theoretical derivation; There is no unified hypothesis and mechanical system for the research object of soil mechanics, and mechanical analysis is not the main means (such as consolidation theory, settlement calculation, stability analysis and seepage analysis are all based on different assumptions about soil); The analysis methods and results of practical engineering problems in soil mechanics are not unique, that is, different results can often be obtained by multiple methods for the same problem (for example, foundation settlement and foundation bearing capacity can be calculated by multiple methods). Soil mechanics has dual characteristics of theory and practice, as Karl Terzaghi, the founder of soil mechanics, said, "Soil mechanics is an art rather than a science" [2].
It is precisely because of this characteristic of soil mechanics that its course content is theoretical, practical, inconsistent and has many formula assumptions. It is necessary to memorize a large number of theoretical methods and empirical formulas and master more complicated drawing and calculation methods, which brings many difficulties to students to learn soil mechanics well and understand and master the theory of soil mechanics.
Second, the problems in curriculum teaching
1. There are many teaching contents and few class hours. Soil mechanics is a professional basic course connecting the preceding with the following, which has the characteristics of wide subject content, strong theory, many empirical formulas, loose knowledge structure and great content jumping. In addition, in recent years, new technologies and theories of civil engineering have emerged constantly, and new technologies and methods have been constantly updated. When studying, students usually feel that there are too many contents to master, which leads to the contradiction between less teaching hours and more teaching contents. At present, according to the training plan and syllabus, the theoretical class hours of soil mechanics course are 48 hours, and the average theoretical class hours of nine chapters of soil mechanics teaching content are less than 6 hours, so it is difficult to master many theoretical laws and more than 100 important concepts and formulas involved.
2. Theory and practice teaching are out of touch. Practice teaching is a necessary aid and guarantee for theoretical study of soil mechanics. However, at present, the practice teaching of soil mechanics is mainly based on indoor experiments, which mainly include classical experiments and confirmatory experiments. The content is old and boring, and students only need to copy the operation, lacking the cultivation of innovative thinking, which does not meet the requirements and characteristics of soil mechanics emphasizing practice and application, and seriously affects the realization of the teaching objectives of the course. Classroom theoretical knowledge and experimental course content are taught and undertaken by theoretical teachers and experimental teachers respectively, which has become a common teaching mode of soil mechanics at present. However, due to the different characteristics of the two types of teachers, lack of communication, discontinuous and incomplete theoretical content and practical content, they can not play a comprehensive role in theory and practice.
3. The theoretical teaching method is single and the content is rigid. The traditional blackboard writing teaching method is mostly used in soil mechanics teaching. Although this method helps students to gradually understand and master the knowledge points in the process of writing on the blackboard, deduction and drawing, as mentioned above, the content of this course is complicated, which leads teachers to only pay attention to writing on the blackboard and students are bored. The introduction of multimedia improves the rigidity of the course content to a certain extent, but in teaching practice, only PPT is played, and there is no blackboard writing process such as formula derivation and drawing, which leads to fast lecture speed, students can't keep up, important knowledge points are not prominent, and students can't grasp it firmly [3].
4. Students' learning enthusiasm and interest are not high. In the teaching process of soil mechanics, students' learning enthusiasm is generally not high and their interest in learning is low. In addition to the students' own reasons, this phenomenon also includes the following two reasons: on the one hand, the reduction of soil mechanics class hours leads to insufficient teaching time, and the teaching method becomes "full-time irrigation", which instills a lot of theories and knowledge in a short time, which makes it difficult for students to digest and master, resulting in weariness of soil mechanics; On the other hand, the characteristics of soil mechanics course, such as many theories, strong practicality, poor consistency of contents, many concepts and many empirical formulas, make it difficult for students to form a complete theoretical and knowledge structure system in the learning process, which leads to weariness of learning.
Third, the thinking and practice of course teaching.
In order to solve the problems existing in the teaching of soil mechanics, improve the teaching quality of soil mechanics and realize the goal of talent training, the following methods and viewpoints are summarized through thinking and practice in the actual teaching process of soil mechanics for discussion.
1. Strengthen the systematization of the theoretical framework of soil mechanics teaching content. Although the content of soil mechanics course is complex, it is also systematic. Generally speaking, soil mechanics can be summarized as a curriculum content framework consisting of three theories and three kinds of engineering and technical problems. The three theories refer to the theory of soil strength, consolidation and permeability, which constitute the theoretical system of soil mechanics and are the basis for solving practical engineering problems. Three kinds of engineering problems include strength problems, deformation problems and seepage problems, among which strength problems also include earth pressure calculation, soil slope stability analysis and foundation bearing capacity [4]. Therefore, in classroom teaching, we should pay attention to the use of theoretical knowledge framework to closely link the course content. We should not only explain the framework of soil mechanics in the course introduction, but also teach it at the beginning of each chapter, so that students can clearly understand the relationship between the learning contents of each chapter and the position and role of this chapter in the whole theoretical framework, and improve the systematic understanding of the content of soil mechanics course.
2. Highlight the experimental class and case teaching to enhance the practicality of the course. Soil mechanics experiment is an important part of soil mechanics teaching and a necessary way to cultivate students' practical ability and improve their ability to analyze and solve problems. Soil mechanics experiment can highlight the following two aspects: on the one hand, establish an open laboratory, effectively use experimental teaching resources, and expand experimental projects outside the syllabus; On the other hand, arrange and encourage students to choose their own topics according to their hobbies or practical engineering problems, and carry out experimental design innovatively. Soil mechanics was born in engineering practice, focusing on solving practical engineering problems. Therefore, in the teaching process of soil mechanics, we should attach great importance to the introduction of engineering cases, such as throwing out practical engineering problems before expounding a theory, then leading out the theoretical content, and finally mastering the methods to solve practical engineering problems through theoretical study. This teaching idea is not only conducive to students' awareness of engineering practice, but also conducive to the absorption and mastery of theoretical knowledge.