For the purpose of preservation of stream environment, accelerating use of thinning wood, cutting down the ex-penses, etc., construction of small dams made of wood has been examined recently. However, the design of wooden dam has been conducted based on experience up to this day, and the methods of designing wooden dams have not been established yet.
The purpose of this study is to examine the methods of designing of small wooden crib dams.
A small wooden crib dam was constructed in the field. Then, horizontal loading tests were conducted using the dam. The methods of design which are suitable for small wooden crib dams were examined based on the data of horizontal loading tests. The results are summarized as follows.
(1) It was confirmed in the horizontal loadig tests and in the stability analysis in which all of forces are taken into acount that the crib structure type wooden dam is completely safe for stability of dam.
(2) It was confirmed in the horizontal loading tests that a method of design in which occurrence of tensile stress is allowed at the upstream end of dam is applicable to design the wooden crib dams for fulfilling their function. A method of design in which occurrence of tensile stress is allowed at the upstream end of dam was presented.
(3) In the horizontal loading tests, the unit weight of boulder packed in the crib is smaller than the value used in the exisiting design criteria. In the subsequent studies, it is necessary to examine the actual condition of the unit weight.
(4) The horizontal loading tests showed that the friction coefficient between dam base and foundation ground is at least 0.91.
(5) The horizontal resistance moment of dam body measured in the horizontal loading tests was at least 2.2 times larger than the shearing resistance moment of cobblestones filled in steel hollow sabo structures calculated by the existing formula.
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